CNN has the answer: (“Kindle Touch’s secret weapon: Lasers“)
Capacitive touch, the touchscreen technology on most devices we’re familar with (such as Android devices, iPhones, iPads, etc.) involves a layer that resides on top of the display* — and when it comes to reading with e-ink displays, introduces a problem of glare.
Infrared laser technology, the kind already found in e-reading devices such asÂ Barnes & Noble’s Nook andÂ Sony e-readers, works a little differently. And, this Amazon believes, creates an overall improved e-reading experience.
“Applying a capacitive-touch layer to e-ink, the black-and-white display that looks like paper, darkens the screen, said Sriram Peruvemba, an executive for E Ink, the company that makes the popular screens in e-readers, in an interview on Wednesday.
For that reason, the Kindle Touch relies on infrared sensors, which are stationed along the edges around the screen to detect when the user’s finger touches a particular spot on the device’s face, an Amazon spokeswoman said.”